JP2008176079A - Cooling system - Google Patents

Abstract

【Task】
Provided is a cooling device that eliminates the problems of dust and dust caused by light transmission in liquid crystal display devices and realizes cooling of liquid crystal panels and the like.
[Solution]
In response to heat generated in the liquid crystal panel or polarizing plate by the light source, the air in the liquid crystal display device that has blocked the flow from the outside to the liquid crystal panel or the heating element that is the polarizing plate is cooled as cooling air by the first cooling means. Thus, the second cooling means is configured to cool the heat generating element by injecting heat to the heat generating element.
[Selection] Figure 1

Description

  The present invention relates to cooling of a high-temperature body in an electronic device, and in particular, a liquid crystal panel in an electronic device such as a liquid crystal display device that displays information such as an image on a screen in an enlarged manner using a light valve element such as a liquid crystal panel, And cooling technology for polarizing plates and the like.

  A liquid crystal projector, which is one of liquid crystal display devices, includes a liquid crystal panel as a light valve, modulates light from a light source, and projects and displays image information on the liquid crystal panel on a screen. With such a configuration, in a liquid crystal projector, light from a light source for projecting image information is absorbed by passing through the liquid crystal layer of the liquid crystal panel, and in a black mask or the like that blocks unnecessary light sources The liquid crystal panel rises in temperature due to the light absorption. In addition, light that does not have a predetermined polarization axis in the light from the light source is absorbed by polarizing plates arranged before and after the liquid crystal panel. The heat accumulated in the polarizing plate is transferred to the liquid crystal panel, leading to an increase in the temperature of the liquid crystal panel.

  An excessive rise in the temperature of the liquid crystal panel leads to a decrease in the reliability of the liquid crystal panel. Therefore, in the liquid crystal projector, as in other electronic devices, the outside air is taken in by a fan installed in the device and blown. Liquid crystal panels and polarizing plates are cooled by applying an air cooling method.

  In recent years, the light emitted to the liquid crystal panel of this liquid crystal display device has become stronger due to the demand for higher brightness of the display screen due to diversification of the usage status of the liquid crystal display device. On the other hand, there is a great demand for low-priced products in the market, and the liquid crystal panels used are becoming increasingly smaller. Combined with these factors, the heating density of the liquid crystal panel is very large. This rise in temperature of the liquid crystal panel accelerates deterioration of the quality of the liquid crystal panel and is a problem for the product life of the liquid crystal display device, and the cooling device is required to improve the cooling capacity corresponding to the rise in temperature. .

  Also, a display device that projects light by irradiating light, such as a liquid crystal display device, displays dust by the projection light when dust and dust are sucked and held in the device, resulting in image quality deterioration. There is also a demand for a cooling method that does not allow external air to flow.

  As a method for improving the cooling capacity while dealing with dust and dust, various liquid cooling methods provided with a liquid refrigerant as described in Patent Document 1 have been studied. In this cooling device, a heat receiving member enclosing a liquid refrigerant is disposed in close contact between the liquid crystal panel and the polarizing plate, and the heat stored in the liquid crystal panel and the polarizing plate is transferred to the liquid refrigerant flowing through the heat receiving member to receive the received liquid. The refrigerant is transferred to a radiator disposed at a position separated by a liquid pump and radiated by the radiator. This liquid refrigerant is circulated between the heat receiving member and the radiator by a liquid pump, and improves the cooling capacity by setting an optimal heat exchange state by heat transfer.

  Further, in Patent Document 2, a heat receiving member having a flow path for flowing a cooling refrigerant is disposed in close contact with only a peripheral region excluding a light transmission region of a liquid crystal panel module irradiated with a light source. The heat stored in the liquid crystal panel is transferred to the cooling refrigerant that circulates around the liquid crystal panel, and the received cooling refrigerant is transferred to the heat dissipating unit located at a position separated by the pump and radiated by the heat dissipating unit. A cooling device is described in which the refrigerant is not directly irradiated with light, and the influence on the projected image quality is avoided.

  Further, there is a cooling device described in Patent Document 3 as a method for cooling a high-temperature body such as a liquid crystal panel while blocking the entry of dust and dust into the liquid crystal display device. In this cooling device, the liquid crystal display device is hermetically sealed by the casing, and the air in the casing is once compressed and then radiated from the nozzle toward the high temperature body. The hot body is cooled by the air flow whose temperature has been lowered by the adiabatic expansion from the nozzle. At this time, the temperature rise that occurs at the time of compression is radiated to the outside air by the radiation fins provided outside the compressor to be brought into contact with the outside air.

  Here, although it is not an example as a cooling means regarding a liquid crystal display device, there exists a cooling device of patent document 4 as a cooling device which cools together using two different cooling means. This cooling device is provided with a cooling circulation system that receives heat from a heating element by a refrigerant and transfers the heat, and a cooling circulation system that circulates a refrigerant whose temperature has been reduced by adiabatic expansion after being compressed by a compressor. This is a cooling system that receives the heat of the heating element, transfers it, and thermally connects the heat of the refrigerant with the other cooling system of the latter to absorb the heat, and dissipates heat in the latter circulation system.

JP-A-1-159684 JP 2005-275189 A JP 2005-148624 A JP 2004-319628 A

The above-described conventional techniques also have the following problems to be solved.
In the cooling device described in Patent Document 1, since light emitted from the light source passes through the liquid refrigerant, there is a new problem that an image of the bubbles and dust is projected on the image when bubbles and dust are mixed in the liquid refrigerant. . In addition, if a temperature difference occurs in the liquid refrigerant, the image may fluctuate due to convection in the liquid refrigerant, and the quality of the liquid refrigerant deteriorates due to the light irradiated from the light source. There is also a problem that the transmittance of the liquid crystal panel is reduced, and the illuminance of the image is reduced.

  In the cooling device described in Patent Document 2, the cooling refrigerant such as the liquid crystal panel is circulated and cooled in a region that avoids the region through which the light emitted from the light source is transmitted. Although the problem of Document 1 can be avoided, it is necessary to efficiently transfer the heat of the liquid crystal panel and the polarizing plate by the light irradiated from the light source to the cooling refrigerant to the periphery. For this reason, a material having a high light transmittance and a high heat conductivity and a high light transmittance and high heat conductivity is used for heat transfer. At present, this high light transmission and high thermal conductivity material is a limited material and is expensive, which is a cost issue as a commercial product. In addition, there is a liquid crystal display device in which dust-proof glass or the like is installed on the surface portion of a high heat conductive material or a liquid crystal panel in order to suck dust and dust by the air sucked by the heat dissipation unit.

  In the cooling device described in Patent Document 3, the pressure and temperature of the injected air can be controlled by controlling the compression state by the compressor, but a large device such as a compressor is required. Furthermore, moisture in the air in the device is liquefied due to rapid cooling of the air due to adiabatic expansion, and these water droplets adhere to a liquid crystal panel or the like, causing deterioration of the image. Further, the temperature fluctuations occur due to the air flow injection period by the compressor, and there is a concern about the influence on the image depending on the period.

  The cooling device described in Patent Literature 4 is provided with an electronic device and a cooling device independently to improve attachment / detachment operability in order to perform attachment / detachment of the cooling device to / from the electronic device. However, in electronic equipment that does not require the attachment or detachment of a cooling device that requires hermeticity, it can be cooled by either one of the cooling methods, and it is not possible to provide two independent cooling circulation systems. The cooling circulation system is thermally connected to perform heat transfer indirectly, and the cooling device has redundancy.

  An object of the present invention is to solve the above-described problems of the prior art and to provide a cooling device that is effective when applied to a liquid crystal projector or the like and that does not attract dust and dust from the outside.

  The cooling device of the present invention includes a first cooling unit that cools the high-temperature body of the electronic device with the circulating first refrigerant, and a second cooling unit that cools the first refrigerant with the circulating second refrigerant. One refrigerant driving means for driving the first refrigerant and the second refrigerant to circulate is provided.

  The cooling device of the present invention includes a first pump chamber that sucks and discharges air and a second pump chamber that sucks and discharges coolant, and the first pump chamber and the second pump chamber are interlocked. A coolant driving unit that operates, a nozzle that jets cooling air to the liquid crystal panel or the polarizing plate, and the cooling air sucked and discharged by the first pump chamber flows to cool the cooling air and An air cooling means installed inside an airtight part of an electronic device containing a liquid crystal panel and a polarizing plate, and sucked and discharged in the second pump chamber. A heat receiving part that cools the heat exchange part with the coolant, a heat radiating part that dissipates the coolant absorbed by the heat receiving part and is installed outside the airtight part, the second pump chamber, and the heat receiving part. Part and said release The cooling fluid connecting the parts so that the cooling fluid is circulated has a configuration and a liquid cooling means including a conduit for flowing.

  According to the cooling device of the present invention, it is possible to provide an electronic device such as a liquid crystal display device having high reliability and high image quality without temperature deterioration of internal components.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 schematically shows a schematic configuration diagram of a liquid crystal display device using a cooling device according to the present invention. The liquid crystal display device is a liquid crystal panel or the like in which a member to be cooled is irradiated with light, and the cooling device of the present invention is preferable for solving the cooling problem peculiar to a liquid crystal panel through which light is transmitted. In addition, the present invention is effective not only in the liquid crystal display device but also in other electronic devices that are required to block external air.

  The liquid crystal display device 1 modulates light emitted from a light source to form image information, and projects the formed image information on a screen for enlarged display. The liquid crystal display device 1 has an optical unit 3 in a housing 2 and projects image information formed by the optical unit 3 onto a screen (not shown) by a projection lens 4. The present invention includes a cooling device 5 for cooling the optical unit 3.

  First, the outline of the function and configuration of the optical unit 3 for forming image information will be described with reference to FIG. The optical unit 3 is a structure for forming image information into an optical image by optically processing light emitted from a light source, and includes an illumination optical system 31, a color separation optical system 32, an optical conversion element 33, and color synthesis. The optical system 34 is configured.

  The illumination optical system 31 reflects the light emitted from the light source 311 by the reflector 312 and emits it as parallel light. The illumination optical system 31 separates the light into a plurality of partial lights by a lens array 313 composed of small lens groups. An image is formed on a liquid crystal panel described later.

  The color separation optical system 32 includes a dichroic mirror 321 (blue separation) and 322 (green and red separation) that transmit and reflect a plurality of partial lights emitted from the illumination optical system 31, and a reflection mirror 323 that reflects partial light. 324 and 325 have a function of separating light of three colors, red, green, and blue.

  The three color lights of red, green, and blue separated by the color separation optical system 32 are projected onto a liquid crystal panel for each color light described later of each optical conversion element 33.

  The optical conversion element 33 is arranged at a position where the liquid crystal panel 332R (G, B) is sandwiched between the incident-side polarizing plate 331R (G, B) and the emission-side polarizing plate 333R (G, B), and is composed of three sets. Yes. Each incident-side polarizing plate 331 (R, G, B) receives light of each color whose polarization direction is aligned in almost one direction, but allows only polarized light in the same direction as the polarization axis of light to pass therethrough. It absorbs other light. Each output-side polarizing plate 333 (R, G, B) transmits light that has passed through the incident-side polarizing plate 331 (R, G, B) out of the light emitted from the liquid crystal panel 332 (R, G, B). Only light having a polarization axis perpendicular to the axis is transmitted, and other light is absorbed. Therefore, the incident-side polarizing plate 331 (R, G, B) and the emission-side polarizing plate 333 (R, G, B) are heated by this absorbed light. In particular, the heat storage in the exit side polarizing plate is large.

  The color synthesis optical system 34 synthesizes image information for each color light that is modulated by each liquid crystal panel 332 (R, G, B) and emitted from each emission-side polarizing plate 333 (R, G, B). Four right-angle prisms are laminated to form an image.

  The projection lens 4 is configured by combining a plurality of lenses, and enlarges and projects the color image formed by the color synthesis optical system 34 on the screen.

  In the liquid crystal display device 1 as described above, for example, polarizing plates 331 (R, G, B), 333 (R, G, B), and liquid crystal panels 332 (R, G, B) that rise in temperature due to light from the light source. ).

The basic configuration of the cooling device 5 of the liquid crystal display device 1 will be described with reference to FIG.
First, it can be said that the features of the present invention that are significantly different from those of a conventional electronic apparatus cooling device are the usage of a pump that drives two refrigerants and the object to be cooled of the two refrigerants driven by the pumps. . As a vortex pump, the pump 51 divides the pump chamber of one vortex pump 51 into a first pump chamber 511 and a second pump chamber 512 to form an independent pump flow path. In the first pump chamber 511 and the second pump chamber 512, the first inflow passage port 513 and the second inflow passage port 514 of the refrigerant, the first outflow passage port 515 of the refrigerant, and the second outflow respectively. A road entrance 516 is provided.

  The refrigerant of the two cooling means is driven by the respective pump chambers. The cooling system in which the refrigerant is circulated by the first pump chamber 511 of the vortex pump 51 includes a first cooling configured by circulatingly connecting the heat receiving member 52, the heat radiating member 53, and the liquid tank 54 through a plurality of pipes 551. Means. The cooling system for transferring the refrigerant by the second pump chamber 512 of the vortex pump 51 includes an air heat exchange member 56 connected by a pipe 552 and a nozzle group 57 including a control member for injecting the transferred refrigerant. And a second cooling means constituted by the injection means.

  The object to be cooled of the liquid crystal display device 1 according to the embodiment of the present invention includes three sets of liquid crystal panels 332 (R, G, B) that transmit light, and polarizing plates 331 (R, G, B), 333 (R , G, B) part. The cooling device 5 for cooling the liquid crystal panel or the like is a cooling method in which low-temperature air is directly jetted onto the plane of the liquid crystal panel or polarizing plate, and a problem that occurs when the light transmission portion of the liquid crystal panel or the like in the liquid cooling method is cooled. It is intended to eliminate.

  As shown in FIG. 1, the cooling device 5 of the present invention has a three-color liquid crystal panel 332 (R, G, B) and a polarizing plate 331 (R, G, B), 333 (R, G) as the object to be cooled. , B), at least three sets of nozzles 57 are provided. When cooling other heat generating electronic components in the liquid crystal display device 1, the same cooling can be achieved by disposing the nozzle 57 facing the object to be cooled as required.

  Here, the configuration and operation contents of the first cooling means and the second cooling means will be described. First, the configuration of the second cooling means for cooling the liquid crystal panel 332 and the polarizing plates 331 and 333, which are direct cooling targets, and the air injection method will be described with reference to FIG.

  The air refrigerant to be injected is actuated by the second pump chamber 512 of the vortex pump 51. That is, air from the inside of the liquid crystal display device 1 that is shut off from the outside and sealed is supplied from a second inflow passage opening 514 provided in the second pump chamber 512, and the second outflow passage opening of the vortex pump 51 is introduced. Air is transferred from 516 to the air heat exchange member 56 connected by the second pipe 552. Inside the air heat exchange member 56, a flow path (not shown) having a fin shape or the like is formed in order to secure a wide area of contact with the air when passing the transferred air and to transfer heat. is doing. The transferred air stays in the air heat exchange member 56 and is then ejected from the nozzle 57 toward the object to be cooled.

  Here, formation of the low temperature (T2) jet air in cooling the high temperature bodies 332, 331, 333 (temperature: Th) will be described with reference to FIGS. FIG. 2 shows a heat conversion state of the cooling device in the present invention.

  The air sucked into the air heat exchange member 56 is the air in the sealed liquid crystal display device 1 and is suitable for blocking dust and dust from the outside, but the high temperature bodies 332, 331, 333. This is air that has been absorbed by (temperature: Th) and absorbed heat (temperature: Tc). The heat (temperature: Tc) of the absorbed air is in a situation where the temperature is slightly lowered (T1) by being thermally diffused and dissipated by the housing 2 or the like while floating inside the liquid crystal display device 1. However, the liquid crystal display device 1 also has other heating elements and the like, and when it reaches a state where it cannot release the absorbed heat, the air remains in a temperature state close to the absorbed temperature (Tc). Become. Even if this heat-absorbed air (temperature: Tc) is injected to the cooled bodies 331, 332, 333 (temperature Th), the high-temperature state of the cooled body cannot be sufficiently cooled. : T2) is required.

  The formation of low temperature (T2) air to be injected will be described. The air heat exchange member 56 is thermally connected to a heat receiving member 52 of a first cooling means described later. The air in the housing 2 is sucked into the air heat change member 56, and the heat (temperature: T1) of the air flowing therethrough is received by the liquid refrigerant flowing through the heat receiving member 52 to obtain a low temperature (T2) wind. It is set as the structure to form. The low-temperature (T2) air that stays in the air heat exchange member 56 and is cooled is continuously injected from the nozzle 57 by the injection control means or intermittently at a predetermined cycle. Injected toward (temperature: Th), the liquid crystal panel 332, the polarizing plates 331, 333 and the like are cooled (temperature: Tc). The air that has absorbed heat (temperature: Tc) from the high temperature bodies 332, 331, 333 again floats in the liquid crystal display device 1 and is dissipated (temperature: T1) through the housing 2 of the liquid crystal display device 1 and the like. Then, it is sucked again by the second inflow passage port 514 of the vortex pump 51, received heat by the refrigerant liquid flowing through the heat receiving member 52 of the first cooling means, and circulated through the nozzle 57 as a low temperature (T2) wind. Will repeat.

  Here, first, heat conversion from a portion close to the object to be cooled will be described in order. The liquid crystal panel 332 and the polarizing plates 331 and 333 are cooled by heat conversion from heat transfer from the interface between the air and the object to be cooled and heat transfer by the air refrigerant. In order to explain these heat conversions, the physical properties of the air involved in the heat conversion of the present invention are shown in FIG. 5 in comparison with water, which is a general liquid refrigerant.

First, the amount of heat Ws received by the air refrigerant at the interface between the object to be cooled and the air is
Ws = (heat transfer coefficient) × (temperature difference) × (contact area) (1)
It is represented by

  Here, the heat transfer coefficient is a function related to the Prandtl number and the heat conductivity, but also changes depending on the flow rate of the refrigerant. In general, the ratio of the liquid refrigerant to the air refrigerant is about 20 times. In other words, in order to obtain a cooling result that is the same temperature as that of cooling with a general liquid refrigerant using an air refrigerant, at least the contact area between the liquid crystal panel, the polarizing plate, etc. and the air needs to be increased by about 20 times. become.

  The liquid crystal panel and the polarizing plate are optically optimally arranged, and it is difficult to provide a heat receiving member that allows liquid refrigerant to flow over the entire surface of each of the liquid crystal panel and the polarizing plate. The heat receiving member must be disposed between 333. For this reason, in the cooling method using a liquid refrigerant, heat transfer is performed with a limited contact area.

  On the other hand, in the cooling method in which air refrigerant is injected, the arrangement of each of the liquid crystal panel 332 and the polarizing plates 331 and 333 is provided with a gap that allows air to flow, and the air refrigerant is provided on both planes. To spray. This means that it is easy to increase the contact area with the refrigerant, and in one example, it can be expanded by about 6 times. Further, a fin member having a contact area of about 3 to 4 times is provided on the attachment members of the liquid crystal panel 332 and the polarizing plates 331 and 333.

  From the above, it is easy to increase the contact area with the air refrigerant by about 20 times the contact area with the water-cooled heat receiving member, and the same amount of heat is transferred to the liquid refrigerant as with the air refrigerant. Is possible.

Next, the heat absorption amount Wt due to heat transfer will be described. The amount of heat absorbed Wt by the heat transfer of the air refrigerant is
Wt = (density) × (specific heat) × (flow rate) × (temperature difference) (2)
It is represented by

  Here, as shown in FIG. 5, since the density of the liquid refrigerant and the air refrigerant is 1: 0.00129 and the specific heat is 1: 0.24, the air driven by the liquid refrigerant cooling drive performance pump. If the flow rate of the refrigerant and the temperature difference are the same, the heat transfer performance by the air refrigerant is about 1/3200 of the heat absorption amount Wt by the liquid refrigerant.

  For this reason, in order to obtain the amount of heat (Wt) necessary for injecting the low temperature (T2) wind to cool to the specified cooling temperature (Tc), it is necessary to significantly increase the flow rate of the injected air.

  Here, as the temperature difference (ΔT) is larger, the amount of heat absorbed can be increased. Therefore, the air injected from the nozzle 57 is higher than the air in the temperature (T1) state radiated by heat diffusion in the housing 2 or the like. As described above, the amount of heat absorbed from the high-temperature body is increased by injecting air cooled to the low temperature (T2) by the liquid refrigerant of the first cooling means. In the air heat exchange member 56, a first cooling means for setting the jetted air to a low temperature (T2) will be described.

  The first cooling means comprises a first pump chamber 511 of the eddy current pump 51, a heat receiving member 52, a heat radiating member 53, and a tank 54 as a closed circulation channel in the first pipe group 551, The liquid refrigerant is transferred in the closed circulation channel, and heat conversion is performed by the two heat exchangers (the heat receiving member 52 and the heat radiating member 53). As described above, the heat receiving member 52 has a flow path through which the liquid refrigerant flows and is thermally connected to the air heat exchange member 56.

  The transferred air in the air heat exchange member 56 is dissipated while staying in the liquid crystal display device 1, but the heat that has not been dissipated is received by the liquid refrigerant flowing through the heat receiving member 52, and the temperature is low. Wind (T2). On the other hand, the received liquid refrigerant (temperature: T <b> 2) is transferred by the pipe 551 connected to the first pump chamber 511 of the vortex pump 51 and transferred to the heat radiating member 53.

  Here, the heat radiating member 53 is attached to the outside of the casing 2 of the liquid crystal display device 1, and the heat (T2) of the received liquid refrigerant is received from the casing 2 by a fan (not shown) attached to the outside of the casing. The outside air (temperature; Ta) is ventilated and cooled, and the heat is radiated outside the housing 2. The radiated refrigerant liquid (temperature: Ta) flows through the pipe 551 and is circulated to the heat receiving member 52.

  That is, the respective refrigerants are circulated and driven to the two cooling units by the vortex pump 51 as one refrigerant driving member. Further, the cooling device 5 for cooling a specific object to be cooled as the liquid crystal display device 1 is realized by combining the advantages of both cooling means.

  Next, the cooling state in the present invention will be described with reference to FIGS. FIG. 3 conceptually shows the relationship between the flow rate of refrigerant and the amount of heat absorbed by the refrigerant. The characteristic curves shown in FIG. 3 are only qualitative, but in both cases, the relationship between the flow rate (Q) of the refrigerant and the endothermic amount (W) is proportional as shown in the above-mentioned (Formula 2). is there.

  By the way, the pump 54 for driving the refrigerant according to the embodiment of the present invention is divided into two parts, the first pump chamber 511 and the second pump chamber 512. The flow rate of the refrigerant liquid driven in each pump chamber is approximately halved (1/2 · Q1) with respect to the flow rate (Q1) of the single-flow vortex pump that does not divide the pump chamber.

  For this reason, when cooling is performed by absorbing heat from an object to be cooled (liquid crystal panel or air) using only the amount of refrigerant (1/2 · Q1) passed through one pump chamber, the amount of heat that can be absorbed is reduced in the amount of refrigerant. W1 = 1 / 2W1 (b). The endothermic amount W1 (A point) necessary for cooling the cooled object temperature (Th) to the predetermined specification cooling temperature (Tc) cannot be obtained. In order to set the object to be cooled (Th) to the specified cooling temperature (Tc), the difference ((W1) − (W1 ′)) from the heat absorption amount (W1) is absorbed by the refrigerant driven by the other pump chamber. Thus, the desired cooling performance is obtained.

  In other words, the cooling device according to the present invention avoids cooling by a liquid refrigerant unsuitable for cooling a liquid crystal panel or the like through which light is transmitted and attempts to cool it by an air refrigerant, and is driven by the first pump chamber 511. A method of cooling (temperature: Tc) the temperature of a heating element (Th) of a liquid crystal panel or the like by the amount of heat absorbed by the liquid refrigerant (b) and the amount of heat absorbed by the air refrigerant driven by the second pump chamber 512 (c). It is realized.

  However, the amount of heat absorbed by the air refrigerant can absorb heat only at about 1/3200 as described above, according to the same flow rate as that of the liquid refrigerant, and in the embodiment in which the pump chamber is divided into two by one drive pump 51. Since the driving flow rates of the liquid refrigerant and the air refrigerant are inevitably the same, the amount of heat absorption (c) is increased as shown in FIG. 2, and the desired amount of heat absorption W1 cannot be obtained. . Therefore, it is indicated that the air refrigerant needs to be accumulated and passed about 3200 times.

The heat conversion state of the cooling system of the present invention will be described with reference to FIG.
FIG. 4 explains the heat conversion state of cooling for the cooling system of the present invention based on the idea of a general cooling system. FIG. 4A schematically shows a basic concept of a general cooling state. FIG. 4B schematically illustrates a cooling situation in the present invention. The horizontal direction (axis) indicates a temporal concept assuming a flow rate related to heat conversion, and the vertical direction (axis) indicates a temperature concept related to heat conversion.

  In general, as shown in FIG. 4 (a), a cooling device for a heating element of an electronic device has a cooling specification temperature (Tc) that is equal to or lower than the allowable temperature (T0) of the cooling object, as the heating temperature (Th) of the cooling object. ), The heat generation temperature (Th) of the object to be cooled is received by the liquid refrigerant of the water-cooled heat receiving member or the air-cooled flow-through air. The amount of heat required to obtain the cooling temperature (Tc) (temperature change: (Th−Tc)), that is, the amount of heat (W1) absorbed by the refrigerant, radiates the heat receiving temperature (Tc) of the refrigerant by the heat radiating member. It is equal to the amount of heat (temperature: (Tc−Ta)) that is the refrigerant temperature (Ta) before the heat treatment, that is, the amount of heat (W2) radiated by the refrigerant. As described above, in every cooling device, transfer of heat is balanced by heat absorption and heat dissipation.

  In the cooling device of the present invention, the cooling state for obtaining a predetermined endothermic amount (W1) by the relationship between the endothermic amount (W1) and the amount of heat released (W2) will be described again, including the content described above with reference to FIG. To do.

  The temperature (Tc) of the air that has been injected and absorbed by the heating element in the liquid crystal display device 1 is thermally diffused and dissipated by the housing 2 while staying in the housing 2, and the temperature of the air (T1) Assuming that The air having the temperature (T1) is sucked from the second inflow passage port 514 of the second cooling means, taken into the pump chamber 512, and flows from the second outflow passage port 516 through the pipe 552 to the air heat exchange member 56. It is transferred to.

  Temporarily, air of temperature (T1) is jetted from the nozzle 57 to the object to be cooled (temperature: Th) and absorbed by the air (temperature: T1) sucked into the pump chamber 512 from the temperature (Th) of the object to be cooled. Since the amount of natural heat radiation in the housing 2 is large, air with a lowered air temperature is preferable from the viewpoint of cooling performance. However, in reality, it is difficult to greatly reduce the air temperature (T1) by only this natural heat dissipation, and thus it can be said that it is difficult to cool to the predetermined cooling temperature (Tc).

  Here, in order to increase the amount of heat absorption from the temperature (Th) of the cooled object by lowering the temperature (T1) of the air to be injected (temperature: T2), the air is passed through the air heat exchange member 56 in the second cooling means. The flow and the stored air (temperature: T1) are cooled (temperature: T2) by the first cooling means. The heat conversion state in the first cooling means is as described above.

  Here, a description will be given assuming that the refrigerant driven by the pump chamber 512 is air while the volumes of the two divided pump chambers of the vortex pump 51 are equal. Using a pump that divides the pump chamber into two parts has the effect of reducing the number of pumps and facilitating ease of assembly and handling, but it goes without saying that the cooling capacity is reduced because the amount of refrigerant is halved. The correspondence will be described later.

  Since there is a difference of about 1: 3200 in the amount of heat transfer between the air refrigerant and the liquid refrigerant, in the cooling device having the same configuration, the cooling by the air refrigerant is the same as the flow rate of air with respect to the cooling by the liquid refrigerant. Unless increased, cooling with the same performance as when receiving heat with a liquid refrigerant will not be performed. In other words, if the injection method of the air injected from the nozzle 57 is continuous, in the present invention in which each refrigerant is driven by one vortex pump 51, the flow rate of the sucked air is the same as the liquid cooling flow rate. This indicates that the predetermined cooling of the high-temperature body cannot be performed. In order to compensate for the shortage of the heat transfer amount, the air injection method is controlled.

  Injecting air from the nozzle 57 for cooling the high-temperature body is performed by driving the vortex pump 51 and feeding a predetermined amount of air into the air heat exchanger 56, and then controlling the injection by the injection control means at a predetermined cycle. is doing. In order to open the nozzle 57 at a predetermined cycle, it is assumed that the air is stored in the air heat exchange member 56 in a slightly compressed state during the injection cycle. It is not something to do. Further, since the injection is released from the nozzle 57 by the injection device (not shown) with the pressure resistance of the nozzle, it is expected that the temperature of the injection air is lowered by a little adiabatic expansion of the air. It is not intended to lower the temperature, but only moderate compression and expansion. The purpose of injection is a method for instantaneously securing an air flow rate in order to transfer heat between air and a cooled object.

  Here, unless the pump flow rate is changed, the flowing air flow rate may be continuous air flow or periodic intermittent injection, but the air refrigerant flow rate is constant within a predetermined time. Therefore, the total endothermic amount is considered to be constant, but the endothermic amount is proportional to the flow rate, so that it is possible to easily increase the flow rate by injection rather than increasing the flow rate of the flowing air refrigerant. It is.

  However, in a pump that does not change the refrigerant driving flow rate, the total driving amount of air does not change. Therefore, in order to absorb a predetermined amount of heat, it accumulates for a predetermined time in order to obtain the total amount of air. Repeating accumulation for a predetermined time, that is, periodic driving is performed.

  Since the heat generating element absorbs heat by periodically injecting the cooling air, the heat generation temperature of the object to be cooled gradually increases after the cooling at the time of injection. If the temperature rise period of the object to be cooled continues for a long time, there is a concern about the effect on the liquid crystal panel. However, the heat generating element is generated by intermittently injecting and cooling the low temperature air before the temperature of the liquid crystal panel rises. The allowable temperature (T0) is averaged.

  On the other hand, since cooling is performed by periodic air injection, the cooling temperature of the object to be cooled varies with the injection period. In order to cope with this problem, it is preferable that the cooling air injection period to the object to be cooled is a field frequency for forming image information or a reduced number of the field frequency.

  A liquid crystal display device or the like sequentially scans pixels constituting an image to form one image with a field frequency. When cooling air is injected in synchronization with the field frequency, the pixel position on the screen that is scanned at the timing when the cooling air is injected is always a constant scanning position. Since it is cooled, the state of the luminance change of the image due to the temperature change on the screen has the same period, so that the visual change can be made constant.

  For example, in the NTSC TV system, the field frequency is 1/60 second, so that it is ejected after accumulating 60 times the previous 1/3200. That is, it is indicated that it is necessary to satisfy an endothermic amount of about 1/50 in the injection of air refrigerant. The nozzle diameter is reduced so that the flow velocity by the nozzle is 50 times that of the conventional liquid refrigerant.

  The present invention provides a control method for intermittently injecting an air flow injected by a nozzle 57 in a temporal manner in order not to increase the flow rate of the vortex pump 51 in total and to prevent the cooling device from becoming large. However, in order to obtain the prescribed cooling temperature by placing the cooling air continuously in order to cool the liquid crystal panel etc. An injection pump and a liquid refrigerant driving pump that cools the air may be provided independently for two.

  Further, it is possible to improve the cooling performance by the driving flow rate of the pump, as in the conventional cooling method.

  Even if the object to be cooled is a heat generating member other than the liquid crystal panel, a similar nozzle can be additionally provided in the vicinity of the object to be cooled.

  Furthermore, the cooling device is also suitable for electronic devices other than liquid crystal display devices that require sealing.

According to the cooling device of the present invention configured as described above, the cooling of the high-temperature body of the liquid crystal display device that projects light can be performed without sucking dust or dust from the outside into the liquid crystal display device. A liquid crystal display device that can efficiently cool the heat generated by the liquid crystal panel or polarizing plate caused by the light source and achieves a visual uniformity in the projected image quality without affecting the image quality. Can be provided.

It is a schematic block diagram of the liquid crystal display device using the cooling device of this invention. It is explanatory drawing of the temperature state of the cooling of the cooling device of this invention. It is a figure which shows the relationship between the flow volume of a refrigerant | coolant, and the heat absorption amount by a refrigerant | coolant. It is a figure explaining the heat exchange state of cooling of the present invention. It is a figure which shows the physical-property value of air and water.

Explanation of symbols

1 ... Liquid crystal display device, 2 ... Housing, 3 ... Optical unit,
331 ... Incident side polarizing plate, 332 ... Liquid crystal panel, 333 ... Emission side polarizing plate,
51 ... Eddy current pump, 511 ... First pump chamber, 512 ... Second pump chamber,
52 ... heat receiving member, 53 ... heat dissipation member, 54 ... pump, 55 ... piping,
551 ... 1st piping group, 552 ... 2nd piping,
56 ... Air heat exchange member, 57 ... Nozzle

Claims (5)

In a cooling device for electronic equipment,
A first cooling means for cooling the high temperature body of the electronic device with the circulating first refrigerant;
Second cooling means for cooling the first refrigerant with a circulating second refrigerant;
A cooling device for electronic equipment, comprising: one refrigerant driving means that drives the first refrigerant and the second refrigerant to circulate individually. In the cooling device for electronic devices according to claim 1,
In the first cooling means, the first refrigerant is a gas, and cools the high temperature body by an air cooling method.
The second cooling means cools the first refrigerant by a liquid cooling method when the second refrigerant is a liquid,
The cooling apparatus for electronic equipment, wherein the refrigerant driving means includes a first pump chamber that discharges the first refrigerant and a second pump chamber that discharges the second refrigerant. The cooling device for an electronic device according to claim 2,
The first cooling means is installed inside an airtight part of an electronic device provided with the high temperature body,
The cooling apparatus for electronic equipment, wherein the second cooling means is configured to cool the second refrigerant by installing a heat radiating part outside the airtight part. In a cooling device for electronic equipment,
Refrigerant driving means including a first pump chamber that sucks and discharges air and a second pump chamber that sucks and discharges coolant, and the first pump chamber and the second pump chamber operate in conjunction with each other;
A nozzle that ejects cooling air to the liquid crystal panel or the polarizing plate, and a heat exchanging portion that cools the air sucked and discharged by the first pump chamber and cools the air, and also flows the cooled air to the nozzle Air cooling means installed inside the airtight part of the electronic device containing the liquid crystal panel and the polarizing plate,
A heat receiving part that cools the heat exchanging part with the coolant sucked and discharged in the second pump chamber, and a heat dissipating part that dissipates the coolant absorbed in the heat receiving part and is installed outside the airtight part And a liquid cooling means including a pipe line through which the cooling liquid circulates and the second pump chamber, the heat receiving part, and the heat radiating part are circulated, and the cooling liquid flows therethrough. Cooling device for electronic equipment. In the cooling device for electronic devices according to claim 4,
The cooling device for an electronic device according to claim 1, wherein the air ejection from the nozzle is performed at a frequency synchronized with a field frequency of the liquid crystal panel or a frequency that is a fraction thereof.

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